Octave (interval region): Difference between revisions

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The '''octave''' (interval ratio '''2/1''') is one of the most basic [[Gallery of Just Intervals|intervals]] found in musical systems throughout the entire world. It is usually called the "interval of equivalence" because tones separated by an octave are perceived to have the same or similar pitch class to the average human listener. The reason for this phenomenon is probably due to the strong region of attraction of low [[Harmonic Entropy|harmonic entropy]], or the strong amplitude of the second [[harmonic]] in most harmonic instruments.
The '''octave''' (interval ratio '''2/1''') is one of the most basic [[Gallery of just intervals|intervals]] found in musical systems throughout the entire world. It has a frequency ratio of 2/1 and a size of 1200 [[cent]]s. It is used as the standard of (logarithmic) measurement for all intervals, regardless if they are justly tuned or not.


It has a frequency ratio of 2/1 and a size of 1200 [[cent]]s. It is used as the standard of (logarithmic) measurement for all intervals, regardless if they are justly tuned or not.
Strangely enough, the Pelog and Slendro scales of the Javanese contain near-octaves even though Gamelan instruments exhibit inharmonic spectra. It is most likely reminiscent of an older musical system, or derived using the human voice instead of inharmonic instruments.


Strangely enough, the Pelog and Slendro scales of the Javanese contain near-octaves even though Gamelan instruments exhibit inharmonic spectra. It is most likely reminiscent of an older musical system, or derived using the human voice instead of inharmonic instruments.
== Octave equivalence ==
 
The octave is usually called the "'''interval of equivalence'''" because tones separated by an octave are perceived to have the same or similar pitch class to the average human listener. The reason for this phenomenon is probably due to the strong region of attraction of low [[harmonic entropy]], or the strong amplitude of the second [[harmonic]] in most harmonic instruments.


== Links ==
== Links ==
* [http://www.kylegann.com/Octave.html Anatomy of an Octave] by [[Kyle Gann]]
* [http://www.kylegann.com/Octave.html Anatomy of an Octave] by [[Kyle Gann]]


== See also ==
== See also ==
* [[Prime interval]]
* [[Prime interval]]
* [[Gallery of Just Intervals]]
* [[Gallery of Just Intervals]]